Large quantities of liquids containing unfiltered particles, such as liquid waste, in the past have been discharged in the environment without filtration. Current federal and state regulations limit the discharge of such liquids and liquid wastes into the environment. U.S. Pat. No. 4,645,605 is directed to filtration of wastes to separate impurities from liquids or gases with biogenetic silica, such as rice hulls, which provides excellent filtration, but which has little heating value and in normal use does not qualify as fuel for industrial boilers, furnaces and kilns.
A number of filter mediums or filter aids have been proposed which when incinerated yield much less ash than the incineration of a conventional product. Some of these products also increase the heating value of the filter cake to a value greater than 5,000 Btu per pound of filter cake so that the filter cake can qualify as fuel for industrial boilers, furnaces and kilns under federal recycling regulations. These products, however, generally have poor filtration characteristics, are very expensive (1.5 to 2.0 times the cost of conventional filter aids) and yield filter cake which is lower in quality than those from conventional filter aids. It would be highly desirable to provide a filter aid which has very good filtration characteristics, good flow rates, which when incinerated produces a minimum amount of ash, raises the heating value of the filter cake to a value greater than 5,000 Btu per pound, and is low cost.